The invention relates to a circulation pump for a conveyed liquid, comprising an electric motor, which is electronically commutated and has a rotor, a stator and a motor circuit, and an impeller that is connected in a rotationally fixed manner to the rotor.
The invention further relates to a heating system for heating a liquid in a basin, comprising a flow-through region for liquid that is positioned outside a liquid-receiving space of the basin, a heater that is disposed at the flow-through region, a control device for the heater as well as a circulation pump.
The invention further relates to a method of determining the flow rate of a liquid through a pipe.
From DE 103 22 366 A1 a heating device for a liquid in a basin is known, which comprises a flow-through section that can be positioned outside a liquid receiving space of the basin. Disposed in the flow-through section is a heater, past which the liquid flows for heating purposes. If the flow rate of the liquid through the flow-through section is no longer adequate, then the heater has to be switched off.
From the background art it is known to use a pressure-operated switch to measure a banking-up pressure in the pipe and respond to variations of the banking-up pressure. It is further known to use a paddle switch with a reed relay to obtain a measure of the flow rate.